Increasing the efficiency of x-ray tubes



W. MEYER.

INCREASING THE EFFICIENCY OF X-RAY TUBES. APPLICATION FILED AUG. 19, 1918.

1,394,569. Patented Oct: 25, 19219 are WILL MEYER, OF CHICAGO, ILLINOH.

INCREASING THE EFFICIENCY OF X-BAY TUBES.

jl,394i,569.

Specification of Letters Patent.

Patented (Pet. 25, 11921;

Application filed August 19, 1918. Serial No. 250,425.

1 0 all whom it may concern:

Be it known that I WILLIAM MEYER"; a

citizen of the United States. residing at Chicago. in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Increasing, the Efliciency of X-Ray Tubesyof which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part -of this specification.

My invention relates to X-ray apparatus and particularly relates to means to increasing the activity and efiiciency of X-ray tubes.

In employing tubes of the self-rectifying type I have found that there is a limitation of the amount of energy that can be passed through the tube and a consequent limitation of the intensity of the X-rays given out thereby, due to an apparent choking orlimiting effect of the tube itself. I have. however, discovered a means for overcoming this limiting action of the tube and for incriasing to a great extent the output of the tu e.

I am unable to state with certainty the theory of the action which my invention or discovery produces, but I shall describe in the following detailed specification how my invention may be practised and employed and I shall reserve the right to propound the correct theory as soon as I become aware of the same.

In the accompanying drawing I have illustrated diagrammatically one manner in which my invention may be practised.

I employ an X-ray tube 1 of the type usually employed in connection with a source of direct current, but I have found that I am able to'operate the same as a selfrectifying tube .and I therefore connect the same to the secondary of a transformer without employing the usual commutating.

device. I

This tube is provided with the usual cathode 2 having a steel jacket 3 over the same and having the usual anti-cathode 4 and the anode proper 5 as is usual in tubes of this character.

The cathode 3 is connected at the terminal 6 to a wire 7 leading to one terminal 8 of the transformer 10, the other terminal 9 being connected to the terminal 11 of the tube 1, which terminal 11 in turn is connected to the anti-cathode 4. An adjustable spark gap upon the tube.

13 is connected in bridge of the tube 1 for limiting the volt-a e which may be impressed hemilliammeter 14 is connected in series relation in the wire 7 to measure the amount of current flow through the tube 1.

The primary winding 15 of the transformer 10 is connected toa suitable source of alternating current 16 which source may be of the voltage of 110 volts, as is usual in distribution circuits. The ratio of the windings 15 to the secondary winding 17 is such that the normal voltage .at the terminals of the secondary is approximately 90,000 volts.

Heretofore the anode 5 has been connected to the anti-cathode 4 by a connection running from the terminal 18 to the terminal 11, so that the two electrodes 5 and& were maintained at substantially the same potential,- when operated from a machine with a high tension rectifier as usually employed.

When the tube is to be operated as a selfrectifying tube this wire connection between 11 and 18 is discarded and no connection made to terminal 18. I have found that under such conditions. when the tube is operated' as a self-rectifying tube, that there is formed a cloud of slightly luminous gases asindicated at 20, slightly above and to the rear of the anti-cathode 4 and between said anti-cathode and the anode 5. I have observed that occasionally. apparently b accident and under conditions over whic no control was exercised, this cloud of gases would be driven down to the position indicated at 20 below the anti-cathode 4 and that at such times the tube operated very quietly and there was a slight increase in current flow through the tube with a correspondingly greater increase in the X-rays thrown off. This action of the cloud of gases 20 is a matter which I can not explain but which is easily observable and which seems to be due to electrical conditions within the tube. I have found that these gases can be controlled by connecting the terminal-'18 of the anode 5 to the neutral point 21 of the secondaries of the transformer 10. By this bonductor 22 Wl'llOh connects the neutral point 21 with the anode 5, the anode is maintained" at a potentlal intermediate that of the cathode 2 or the anti-cathode t.

The connection of the anode to the neutral point 21 has the effect not only, of drawn the cloud of gases-20 to the position 20',.an

thereby increasing the quiet and steady operation of the tube. but of vastly increasing the output of the tube. Whereas the best amperage that could be forced through a tube operated under the conditions of the prior art was 20 milliamperes on an experiment which I have conducted, I have found that byemploying the connections indicated in the drawing I have increased the output to 45 milliamperes. or 125%.

The neutral point 21 is connected by the wire 25 through the high resistance rods 23 and 24 to the terminals 26 and 27 of the primary winding 15 of .the transformer.

One side of the transformer primary 15 is grounded as indicated-at 28. The resistance of the connections 23 and 24 is in the neighborhood of 15,000 ohms. I may employ a grounded connection at 29 instead of the grounded connection indicated at 28.

I have found that merely connecting the anode 18 to ground directly without running the connection to the neutral point of the secondary of the transformer increases the efficiency of the tube and is able to control the cloud of gases 20, making the tube operate more quietly and more efficiently.

I consider that the control of the cloud of gases 20 is exercised by varying the potential of the anode 5.; In case of the earth connection, the earth appears to be a large reservoir of negative electricity and thus fixes the potential of the anode 5.

I do not intend to be limited to the details shown or described and do not intend my invention to be limited by my, inability to state the theory of operation.

I claim:

1. In combination, a source of current comprising a winding, said winding having end terminals and having an intermediate tap, an X-ray tube having an anti-cathode, an electrode constituting the cathode for. said anti-cathode, and an anode, means for connecting the terminals of said winding to said cathode and said anti-cathode respectively and means for connecting the anode to the intermediate tap.

. 2. In an'X-ray tube, a cathode, an anticathode, said anti-cathode being adapted to have a cloud of gases normally above and back of the same and a third electrode for driving the cloud of ases below the. anticaltgode to improve t'e operation of the tu 7 the anti-cathode electrodes between which,

an electronic flow is set 11 4. In combination, an -ray tube having an anti-cathode, an electrode constituting the cathode for said anti-cathode and an anode, a transformer having a secondary winding connected to the cathode and the anti-cathode and means connecting the anode to the transformer winding, between said first connections.

5. In combination, an X-ray tube having a cathode, an anti-cathode and an anode, a transformer having primary and secondary windings, means connecting the terminals of the secondary winding of the transformer to the cathode and the anti-cathode respectively, said secondary transformer winding having a tap leading from the central portion thereof, a conductor connecting said tap to the anode and a ground connection for said central tap.

6. In combination, an X-ray-tube having a cathode, an anti-cathode and an anode, means for connecting the anode to ground and means connected across the cathode and anti-cathode independently of the anode for subjecting the cathode and anti-cathode to a difference of potential to cause the generation of X-rays.

7. In combination, an X-ray tube having an anti-cathode, an electrode constituting the cathode for said anti-cathode, and an anode, means for impressing a difference of potential of alternating character upon the cathode and cooperating anti-cathode, and means for maintaining the anode at an intermediate otential.

8. In an -ray system, a primary winding having one side thereof grounded, a source of alternating current connected to said Winding, a secondary winding, an X-ray tube having its cathode and anti-cathode connected to the terminals of said secondary winding, a bridge of high resistance across the terminals of the primary winding, a tap from the central part of the secondary winding connected to the "central part of said bridge and to the anode of said tube.

In witness whereof, I hereunto subscribe my name this 17th day of August, A. D. 1918.

WILLIAM MEYER. 

